import math
import random

def B(a):
    return math.pi * a ** 2

def C(a):
    return 2 * math.pi * a

def D(a, b):
    return random.randint(a, b)

def E(a):
    if a <= 1:
        return False
    for i in range(2, int(math.sqrt(a)) + 1):
        if a % i == 0:
            return False
    return True

def F(a):
    if a == 0:
        return 1
    return a * F(a - 1)


print("圆的面积:", B(5))

print("圆的周长:", C(5))

print("随机整数:", D(1, 10))

print("是否为质数:", E(7))

print("阶乘:", F(5))